engleski

Liposomes-in-vehicles: the influence of liposomes and vehicle type on drug release

For more than three decades liposomes have been widely investigated as carriers for (trans)dermal delivery of drugs. However, most of the reports on conventional liposomes describe localized effects, as a result of vesicles accumulation in the stratum corneum or upper layers of the epidermis [1]. To overcome these limitations, new types of liposomes with pronounced membrane elasticity, such as deformable (elastic) liposomes, ethosomes, invasomes and propylene glycol-containing liposomes have been investigated [2, 3]. In the present study we compared different classes of liposomes in order to find optimal formulation for (trans)dermal delivery of a hydrophilic model drug (diclofenac sodium). To achieve a proper viscosity for the skin application, liposomes were incorporated into two different vehicles, namely hydrogel and cream base, and investigated for the influence of both liposome and vehicle type on the drug release. Conventional (CL), deformable (DL) and propylene glycol liposomes (PGL) embodying 10% (PGL-10) or 30% w/v of propylene glycol (PGL-30), were prepared by the film hydration method followed by extrusion using two different lipid concentrations (26 and 52 mM). Concentration of the drug was kept constant for all preparations (47 mM). The size, surface charge, membrane elasticity and entrapment efficiency were found to be affected by the vesicle lipid concentration, the presence of the surfactant and propylene glycol. The mean diameters of all of the extruded liposomes prepared with the lower lipid concentration were in the range of 147 (DL) to 165 nm (PGL-30). The highest entrapment of the drug was achieved by PGL-30 (>160 μg/mg lipid) and the lowest by DL. Regarding the degree of liposome membrane elasticity determined, DL and PGL-10 were calculated to have an almost 5-fold higher elasticity than CL. Evaluation of the in vitro drug release from different liposomes-in-vehicle formulations has proven influence of both the type of liposomes and the vehicle on the drug release profile. The release of the drug from the cream base was significantly decreased, as compared to the hydrogel. Similar release profiles were achieved with both types of elastic vesicles (DL and PGL), while the slowest release was observed for CL, regardless of the vehicle used. In conclusion, propylene glycol liposomes-in-hydrogel is considered as the optimal formulation for improving skin delivery of hydrophilic drug. However, the skin permeation studies need to be performed to confirm the superiority of formulation

Liposomes; Elasticity; Propylene glycol: Hydrogel; Cream; Release

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